Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description nonetheless adds genuinely non-obvious behavior: pre-2024 filings return `structured: false` with bounded plain text rather than empty data, which prevents an agent from misreading an empty result as no holdings.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action and identifier, and every sentence carries substance (owners returned, Item 4 purpose text, legacy fallback). The final sentence is long, but the detail is load-bearing rather than filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a parse tool with full schema coverage and an output schema present, the description is close to complete: it names the input, sketches the returned fields, and flags the legacy-format edge case. Pagination and any size limits on the plain-text fallback are the only notable omissions.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all four parameters (including the cik/ticker aliases) are already documented in the schema. The description only adds that ticker_or_cik is the same value passed to sec_13d_filings, which is marginal added meaning — thus the baseline 3.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb ("Parse") and resource ("ONE Schedule 13D or 13G filing"), scopes it to a single filing via issuer + accession_number, and names the sibling sec_13d_filings as the source of the identifier. An agent can distinguish this from sec_13d_filings and sec_13d_amendment_diff without opening a schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly tells the agent to obtain the accession_number from sec_13d_filings, which establishes the call sequence. It does not, however, mention when to prefer sec_13d_amendment_diff or how to handle amendment filings, so routing between the three 13D tools is only partially resolved.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.